1. Field of the Invention
The present invention pertains to surgical cutting instruments and, more particularly, to such instruments designed for use in arthroscopic surgery and similar surgery sites.
2. Discussion of the Prior Art
Power driven surgical cutting instruments have been used for surgery in the body for some time. U.S. Pat. No. 3,884,238 to O'Malley et al, U.S. Pat. No. 3,994,297 to Kopf, U.S. Pat. No. 4,011,869 to Seiler, Jr., U.S. Pat. No. 4,099,529 to Peyman, U.S. Pat. No. 4,203,444 to Bonnell et al, U.S. Pat. Nos. 4,246,902, 4,577,629 and 4,573,234 to Martinez, U.S. Pat. No. 4,274,414 to Johnson et al, U.S. Pat. No. 4,314,560 to Helfgott et al, U.S. Pat. No. 4,517,977 to Frost and U.S. Pat. No. 4,589,414 to Yoshida et al are representative of instruments producing a shearing action to cut bodily tissue by reciprocating or rotating an inner member within an outer tube where the outer tube has a cutting port therein and the inner member has a cutting edge cooperating with the port to produce the shearing action as the inner member reciprocates or rotates past the cutting port. While such instruments are presently used for various surgical procedures, most of the instruments were originally developed for vitrectomy procedures, and the mechanical structure of the vitrectomy instruments has been adapted for use in arthroscopic and other surgical procedures since the rotary or reciprocating cutting action is used in the same manner to cut the various tissues in various parts of the body.
It has been found in arthroscopic surgery that rotary and reciprocating cutting instruments do not satisfy the wide spectrum of requirements based on the cutting and aspirating characteristics needed for various arthroscopic surgical procedures and the individual styles of surgeons.
The Whipple et al U.S. Pat. Nos. 4,522,206 and 4,662,371 disclose surgical cutting-suctioning instruments having an outer support tube terminating distally at a fixed jaw with a movable jaw pivotally mounted thereon by stub pins on an axis below the longitudinal axis of the outer tube 10. An inner tube extends within the outer tube and has an elongated tang hingedly connected with the movable jaw to cause pivotal movement thereof in response to reciprocating movement of the inner tube created by a squeezing action on an actuating lever relative to a fixed handle. The fixed jaw has a closed floor with steps thereon while the movable jaw defines a cavity that opens into a throat for passage of cut material into the inner tube. The configuration of the movable jaw is such that the jaw is mounted on spaced legs defining the throat which is narrower than the passage formed by the inner and outer tubes for removal of cut material. The surgical instrument is specifically designed to be operable similar to hand-actuated instruments with which surgeons are most familiar; and, upon opening of the jaws of the instrument, differential fluid pressure acts endwise through the opened jaws, the open throat and the fragment transport passage to draw the tissue fragment cut by closing action of the jaws and transport it through and out of the instrument. The open throat is defined between a proximal portion of the movable jaw and the adjacent side of the outer hollow member and has a width corresponding substantially to the spacing between the inner surfaces of the sides of the pivotal jaw, that is, narrower than the remaining passage. In operation, as the jaws open, suction draws the severed tissue fragment toward the throat which is a constriction in the flow passage. The surgical instrument may be powered, e.g., by use of a crank on a motor, a wobble plate, or other means of converting rotational motion-to-axial motion. The surgical instrument of the Whipple et al patents is operable in a manner similar to a punch forcep but suffers the disadvantages of being slow, inefficient and expensive; and, additionally, by having a throat defined between the stationary and movable jaws, a constriction is created reducing suction and inhibiting flow of cut tissue through the inner tube. Furthermore, having suction concentrated at the edges of the jaws when the jaws are open is not desirable for scissor-like cutting operation since it move tissue to be cut causing difficulty in making precision cuts.